MK-Ultra can refer to:

1)MK-ULTRA (also spelled Mk-Ultra, MK Ultra, or Mk Ultra) was a hardcore/thrash band from Chicago, Illinois formed in 1993. They were known for their fast music and outspokenness on political and social topics ranging from capitalism to Christianity. Due to "legal troubles", the band was forced to drop the name "MK-ULTRA" in 1999. They finally broke up in 2000, although the band continued donating songs to compilations for some years afterwards.
http://en.wikipedia.org/wiki/MK-ULTRA_(Chicago_band)

2) Psytrance artist Jean-François Bire, also known as Jeff Bire, member of Underhead. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.